One rolling mill of this type, a so-called Platzer rolling mill, is described in U.S. Pat. No. 5,035,131 owned by common assignee Mannesmann A. G. U.S. Pat. No. 5,025,131 discloses four rolling segments distributed symmetrically over the circumference of the support body of the rolling mill. In that mill, the chocks, the support body and cages holding the two sets of intermediate and work rolls must be removed from the roll stand after the end of the useful life of a rolling segments has been reached, for instance, after about 25 hours. The assembly is turned 90.degree. and reinstalled into the stand. This operation disadvantageously requires the shutting down of production.
There are instances, however of rolling mills of the above mentioned type in which the useful life of the rolling segments is less than 25 hours. Such cases occur, for instance, upon the rolling of alloy steels having high resistance to deformation, or else upon the rolling of structural steels at low rolling temperatures, in which connection high reshaping resistances also result. If the rolling forces are, for instance, twice as great in this case, this means a reduction of the useful life of the rolling segments by a factor of eight.
To transport the sets of rolls out of the stand after about three hours in order to change the rolling segments, means an unacceptable interruption of production of at least 30 to 40 minutes. Furthermore, there is the disadvantage that each set of rolls is of great weight and can be turned only with difficulty and by means of heavy devices. For the depositing of the individual sets of rolls, a free space is required and the handling of the set of rolls ties up a heavy crane.
The problems and disadvantages described above show that it may be more advantageous in certain applications if one could bring the different rolling segments into rolling action sequentially one after the other without removing the set or sets of rolls from the stand or without turning the chocks and support body. This would also lead to the advantage that rolling segments of different geometrical shape can be brought into action in a very short period of time. The present invention includes the above objects.
To achieve these and further objectives, the support body of the present invention comprises a plurality of rolling segments including associated rolling surfaces which are arranged on a turret head which can be mounted, such as, for example, by clamping in three planes and which is rotatable by motor around an axis parallel to the axis of the support body. The turret head is mounted on the support body within a recess thereof. The turret head permits the different rolling segments, and thus the rolling surfaces thereof to be brought into action one after the other by rotating the turret head around its longitudinal axis thereby enabling a very rapid change of the rolling segments without the necessity of removing the work and intermediate rolls.
The turret head is preferably composed of a cylindrical base member on which the rolling surfaces of the rolling segments are formed in spaced relation to each other on correspondingly shaped work pieces which are firmly attached to the base member. Between or alongside the work pieces support bearings having partially cylindrical slide surfaces are arranged, which, receiving the cylindrical regions of the base member, support and center the base member with respect to the support body. In this way, there is created a structural part for practicing the present invention in a particularly preferred manner. The described arrangement provides in addition to the rapid replacement of the rolling segments, a particularly dependable and stable support.
If, in accordance with another feature of the present invention, the rolling segments and their rolling surfaces are provided with different geometries, a particular advantage of the invention becomes evident. By simple turning of the turret head, it is possible to produce different profiles of the material being rolled by bringing rolling surfaces of different geometry into action for the supporting of the intermediate and working rolls.
To lock the turret head during the rolling operation, in accordance with another feature of the invention, the base member of the turrent head is clamped against the support bearings in a direction perpendicular to the rolling path and is locked against turning by means of clamping or wedge elements which engage or wedge against flattened circumferential regions of the cylindrical base member. In one particularly preferred embodiment the base member is member is hydraulically centered and secured to prevent movement thereof in the axial direction.
For the turning of the turret head through a specific angle, it is provided, in accordance with the present invention, that a swing drive be arranged or adapted for connection outside of the support body, said drive engaging via a pinion shaft with a gear wheel arranged on the cylindrical base member. For this purpose, there can be used a known swing drive with push-on gearing with which it is possible, by means of a toothed coupling, precisely to predetermine and effect an angular turning of the structural part to be swung. The angular movement corresponds to the position of the rolling surfaces of the rolling segments on the turret head.
The present invention enables, in simple fashion, either to replace worn rolling segments by turning the turret head or to adjust for different sections of rolled strip by turning to differently shaped rolling segments. While the simple turning of the turret head requires a less frequent removal of the rolling segments and thus considerably reduces the standstill times, the possibility of being able to choose the most suitably shaped rolling segment permits to influence the profile of the rolled material with very simple means.